1. Field of the Invention
The present invention relates to integrated circuit devices, and more particularly, to an integrated circuit device with serial bus communication modes.
2. Discussion of the Related Art
As is well known, a smart card interfaces with a smart card reader on the basis of International Standardization Organization (ISO) 7816 standard (hereinafter, referred to as ISO-7816 standard). The smart card provides eight pins. Specifically, the smart card includes a power supply voltage terminal (VDD), a ground voltage terminal (VSS), a reset terminal (RST), a clock terminal (CLK), an input/output terminal (SIO), a high-voltage terminal (VPP) and two reserved terminals.
The smart card as an integrated circuit device has been developed to be operable in other serial bus communication modes, as well as an ISO-7816 communication mode. For example, the serial bus communication mode may be a universal serial bus communication mode (hereinafter, referred to as USB communication mode). In the case of such a smart card, the reserved terminals will be used to transmit a data in the USB communication mode. Accordingly, the smart card may operate in the ISO-7816 communication mode (hereinafter, referred to as ISO communication mode) or the USB communication mode so as to interface with an external device (e.g., a smart card reader).
Although the smart card supports both the ISO and USB communication modes, the smart card must operate in either the ISO communication mode or the USB communication mode according to the communication mode supported by the external device. This means that the communication mode of the conventional smart card must be fixed to any one of the communication modes. Consequently, the smart card cannot use one of the ISO and USB communication modes.